The present invention relates to refractory chrome-magnesia bricks and compositions made from a granular fused material and processes for their production. The term "fused material" refers to a product which is obtained by heatng a starting material to its molten state, pouring the melt into a vessel or a mold and then letting the melt solidify in the vessel or mold.
Chrome-magnesia bricks made from fused material are known. Referred to also as fused-cast bricks, such bricks can be made from green chromium oxide (a commercial pigment dye), and high-grade calcined or raw magnesite or purer types of magnesia. U.S. Pat. No. 2,271,362 discloses chrome-magnesite fusion bricks having a composition of 79% Cr.sub.2 O.sub.3, 20.6% MgO and 0.4% CaO. These bricks can serve as lining in glass tank furnaces, but only below the melt level, because above the melt level they are eroded quickly. Also known are fused-cast bricks of pure MgO.Cr.sub.2 O.sub.3, that is spinel magnesium chromite, which consists of about 79.2% Cr.sub.2 O.sub.3 and 20.8% MgO. These bricks, however, show unfavorable properties in the slagging test (Brit. Pat. No. 621,736).